fix clock rate computation with standard RTP payload type (#123)

go.mod

@@ -5,7 +5,7 @@ go 1.15
 require (
 	github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751 // indirect
 	github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d // indirect
-	github.com/aler9/gortsplib v0.0.0-20201128222126-daebb85421c6
+	github.com/aler9/gortsplib v0.0.0-20201129151859-4e8fa2e4ab97
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/fsnotify/fsnotify v1.4.9
 	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51

go.sum

@@ -2,8 +2,8 @@ github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751 h1:JYp7IbQjafo
 github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
 github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d h1:UQZhZ2O0vMHr2cI+DC1Mbh0TJxzA3RcLoMsFw+aXw7E=
 github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d/go.mod h1:rBZYJk541a8SKzHPHnH3zbiI+7dagKZ0cgpgrD7Fyho=
-github.com/aler9/gortsplib v0.0.0-20201128222126-daebb85421c6 h1:Gm50pyakl7N4eTf8w7KVHMK1MXsk+x9e3cj+8hg/0i8=
-github.com/aler9/gortsplib v0.0.0-20201128222126-daebb85421c6/go.mod h1:8P09VjpiPJFyfkVosyF5/TY82jNwkMN165NS/7sc32I=
+github.com/aler9/gortsplib v0.0.0-20201129151859-4e8fa2e4ab97 h1:OLxB4ehf7Y+boNtL8QxiH2egfsyeTWR/akVXSyPLMXM=
+github.com/aler9/gortsplib v0.0.0-20201129151859-4e8fa2e4ab97/go.mod h1:8P09VjpiPJFyfkVosyF5/TY82jNwkMN165NS/7sc32I=
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=